/* styles/00-tokens.css */
/* Layout concept: a lesson is a circuit — one wire runs down the margin and each
   segment of the lesson sits on it like a gate. |0⟩ is cobalt, |1⟩ is amber,
   and complex phase is drawn as an angle (and a hue) wherever amplitudes appear. */
:root {
  --paper: #f4f6f9;
  --panel: #ffffff;
  --panel-2: #eef1f6;
  --ink: #0f1a2b;
  --ink-2: #44526a;
  --ink-3: #606d82;
  --rule: #d8dfe9;
  --accent: #2c47d0;
  --accent-ink: #ffffff;
  --accent-soft: #e5eafc;
  --one: #c86a06;
  --one-soft: #fbead6;
  --good: #0f7a57;
  --good-soft: #dcf2e8;
  --bad: #c42f3a;
  --bad-soft: #fbe2e4;
  --warn: #9a6200;
  --warn-soft: #fbefd5;
  --shadow: 0 1px 2px rgba(15, 26, 43, 0.06), 0 4px 16px rgba(15, 26, 43, 0.06);
  --phase-l: 0.62;
  --phase-c: 0.16;

  --font-display: 'Bricolage Grotesque', 'Avenir Next', 'Segoe UI', system-ui, sans-serif;
  --font-body: 'Atkinson Hyperlegible Next', 'Atkinson Hyperlegible', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --font-mono: 'Atkinson Hyperlegible Mono', ui-monospace, 'SF Mono', Menlo, Consolas, monospace;

  --t-xs: 0.78rem;
  --t-sm: 0.9rem;
  --t-md: 1.0625rem;
  --t-lg: 1.25rem;
  --t-xl: 1.6rem;
  --t-2xl: 2.15rem;
  --t-3xl: 2.9rem;

  --s-1: 4px;
  --s-2: 8px;
  --s-3: 12px;
  --s-4: 16px;
  --s-5: 24px;
  --s-6: 32px;
  --s-7: 48px;
  --s-8: 72px;

  --r-sm: 6px;
  --r-md: 10px;
  --r-lg: 16px;
  --measure: 68ch;
  --wire: 2px;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #0d131c;
    --panel: #141c28;
    --panel-2: #1b2534;
    --ink: #e7edf6;
    --ink-2: #a9b6c8;
    --ink-3: #8592a8;
    --rule: #263246;
    --accent: #8197ff;
    --accent-ink: #0b1020;
    --accent-soft: #1d2747;
    --one: #f2a447;
    --one-soft: #3a2a14;
    --good: #45c495;
    --good-soft: #12301f;
    --bad: #ff7b84;
    --bad-soft: #3a1a1e;
    --warn: #e8b04a;
    --warn-soft: #33270f;
    --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 6px 20px rgba(0, 0, 0, 0.25);
    --phase-l: 0.74;
    --phase-c: 0.14;
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --paper: #0d131c;
  --panel: #141c28;
  --panel-2: #1b2534;
  --ink: #e7edf6;
  --ink-2: #a9b6c8;
  --ink-3: #8592a8;
  --rule: #263246;
  --accent: #8197ff;
  --accent-ink: #0b1020;
  --accent-soft: #1d2747;
  --one: #f2a447;
  --one-soft: #3a2a14;
  --good: #45c495;
  --good-soft: #12301f;
  --bad: #ff7b84;
  --bad-soft: #3a1a1e;
  --warn: #e8b04a;
  --warn-soft: #33270f;
  --shadow: 0 1px 2px rgba(0, 0, 0, 0.3), 0 6px 20px rgba(0, 0, 0, 0.25);
  --phase-l: 0.74;
  --phase-c: 0.14;
  color-scheme: dark;
}

/* styles/10-base.css */
*, *::before, *::after { box-sizing: border-box; }
[hidden] { display: none !important; }

html { -webkit-text-size-adjust: 100%; }

body {
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: var(--t-md);
  line-height: 1.6;
  margin: 0;
  min-height: 100vh;
}

h1, h2, h3, h4 {
  font-family: var(--font-display);
  font-weight: 650;
  line-height: 1.15;
  letter-spacing: -0.015em;
  text-wrap: balance;
  margin: 0;
}
h1 { font-size: var(--t-3xl); }
h2 { font-size: var(--t-2xl); }
h3 { font-size: var(--t-xl); }
h4 { font-size: var(--t-lg); }

p { margin: 0; }
a { color: var(--accent); text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
code, kbd, samp { font-family: var(--font-mono); font-size: 0.92em; }
code { background: var(--panel-2); padding: 0.08em 0.35em; border-radius: 4px; }
strong { font-weight: 650; }
hr { border: 0; border-top: 1px solid var(--rule); margin: var(--s-5) 0; }

:focus-visible {
  outline: 3px solid var(--accent);
  outline-offset: 2px;
  border-radius: 4px;
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: var(--t-xs);
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.muted { color: var(--ink-2); }
.small { font-size: var(--t-sm); }
.mono { font-family: var(--font-mono); }
.num { font-variant-numeric: tabular-nums; }
.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap;
}

/* ---------- Prose (rendered Markdown) ---------- */
.prose { display: grid; gap: var(--s-3); max-width: var(--measure); min-width: 0; }
.prose ul, .prose ol { margin: 0; padding-left: 1.3em; display: grid; gap: var(--s-1); }
.prose h4 { margin-top: var(--s-2); }
.prose .math-display { overflow-x: auto; overflow-y: hidden; padding: var(--s-1) 0; }
.prose .md-aside {
  border-left: 3px solid var(--rule);
  padding: var(--s-1) 0 var(--s-1) var(--s-4);
  color: var(--ink-2);
}
.katex { font-size: 1.08em; }
.katex-display { margin: 0.4em 0; }
/* Inline math glued to its punctuation (md.js): no line break between them, but a long formula
   still breaks after = or + as before, because a break inside it follows the .katex's own value. */
.nobr { white-space: nowrap; }
.nobr > .katex { white-space: normal; }
.tex-fallback { white-space: pre-wrap; }
/* A read-along reference ([[nc: …]] in md.js), shown only with "Read along with Nielsen & Chuang"
   on: quieter than the sentence it sits in, so the explanation still reads first. */
.nc-ref { color: var(--ink-2); font-size: 0.92em; }
.nc-ref a { color: inherit; text-decoration-color: var(--ink-3); }
.nc-ref strong { font-weight: 600; }

/* ---------- Buttons ---------- */
.btn {
  -webkit-appearance: none;
  appearance: none;
  font: inherit;
  font-size: var(--t-sm);
  font-weight: 600;
  line-height: 1.2;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--s-2);
  min-height: 40px;
  padding: 0.55em 1.05em;
  border-radius: var(--r-sm);
  border: 1px solid var(--rule);
  background: var(--panel);
  color: var(--ink);
  cursor: pointer;
  transition: background 0.12s, border-color 0.12s, transform 0.06s;
  text-decoration: none;
}
.btn:hover { border-color: var(--ink-3); }
.btn:active { transform: translateY(1px); }
.btn[disabled] { opacity: 0.45; filter: grayscale(0.7); cursor: not-allowed; transform: none; }
.btn.primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.btn.primary:hover { filter: brightness(1.08); }
.btn.ghost { background: transparent; border-color: transparent; color: var(--ink-2); }
.btn.ghost:hover { background: var(--panel-2); color: var(--ink); }
.btn.small { min-height: 32px; padding: 0.35em 0.75em; font-size: var(--t-xs); }
.btn-row { display: flex; flex-wrap: wrap; gap: var(--s-2); align-items: center; }

/* ---------- Form inputs ---------- */
input[type="text"], input[type="number"], textarea, select {
  font: inherit;
  color: var(--ink);
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--r-sm);
  padding: 0.5em 0.7em;
  min-height: 40px;
  max-width: 100%;
}
input[type="text"]:focus, textarea:focus, select:focus { border-color: var(--accent); outline: none; box-shadow: 0 0 0 3px var(--accent-soft); }
textarea { width: 100%; min-height: 7em; resize: vertical; line-height: 1.5; }
input[type="range"] { accent-color: var(--accent); width: 100%; }
input.math-input { font-family: var(--font-mono); }
label { cursor: pointer; }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.001ms !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}

/* KaTeX's hidden MathML is absolutely positioned; anchor it so it can't widen scrolling boxes. */
.katex { position: relative; }

/* katex */
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/* seo/notes.css */
/* Static pages (SPEC §10): lessons and toolkit topics as one readable page each, the toolkit index,
   About, and the few additions the home needs (it is pre-rendered inside the app page with the app's
   own classes). Built on the site's tokens and base styles (00-tokens.css, 10-base.css); every class
   is prefixed sp-. Light and dark follow the device setting through the tokens. */

.sp { --sp-col: 46rem; }
body.sp { display: flex; flex-direction: column; }
.sp-main { width: 100%; max-width: var(--sp-col); margin: 0 auto; padding: var(--s-4) max(16px, env(safe-area-inset-left, 0px)) var(--s-7); display: grid; gap: var(--s-6); min-width: 0; flex: 1 0 auto; }
.sp-main > * { min-width: 0; }
.sp-vh { position: absolute !important; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.sp-skip { position: absolute; left: 8px; top: -60px; z-index: 20; background: var(--panel); padding: var(--s-2) var(--s-3); border-radius: var(--r-sm); }
.sp-skip:focus { top: 8px; }

/* ---------- Header and footer ---------- */
.sp-top { border-bottom: 1px solid var(--rule); background: color-mix(in srgb, var(--paper) 92%, transparent); }
.sp-top-in { max-width: 1240px; margin: 0 auto; padding: var(--s-3) max(16px, env(safe-area-inset-left, 0px)); display: flex; align-items: center; gap: var(--s-4); flex-wrap: wrap; }
.sp-brand { display: inline-flex; align-items: baseline; gap: var(--s-2); font-family: var(--font-display); font-weight: 750; font-size: var(--t-lg); color: var(--ink); text-decoration: none; letter-spacing: -0.02em; }
.sp-brand-ket { font-family: var(--font-mono); font-weight: 500; color: var(--accent); font-size: 0.95em; }
.sp-nav { display: flex; gap: var(--s-1); flex-wrap: wrap; }
.sp-nav a { color: var(--ink-2); text-decoration: none; font-size: var(--t-sm); font-weight: 600; padding: 0.35em 0.7em; border-radius: var(--r-sm); }
.sp-nav a:hover, .sp-nav a[aria-current="page"] { background: var(--panel-2); color: var(--ink); }
.sp-open { margin-left: auto; }

.sp-foot { border-top: 1px solid var(--rule); background: var(--panel); }
.sp-foot-in { max-width: 1240px; margin: 0 auto; padding: var(--s-6) max(16px, env(safe-area-inset-left, 0px)) var(--s-7); display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 15rem), 1fr)); gap: var(--s-5) var(--s-6); }
.sp-foot-col { display: grid; gap: var(--s-2); align-content: start; min-width: 0; }
.sp-foot-h { font-family: var(--font-mono); font-size: var(--t-xs); letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-3); font-weight: 600; }
.sp-foot-h a { color: inherit; }
.sp-foot ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 2px; font-size: var(--t-sm); }
.sp-foot-note { font-size: var(--t-sm); color: var(--ink-2); max-width: 32ch; }

/* ---------- Buttons and small type ---------- */
.sp-btn { display: inline-flex; align-items: center; justify-content: center; gap: var(--s-2); min-height: 44px; padding: 0.55em 1.1em; border-radius: var(--r-sm); border: 1px solid var(--rule); background: var(--panel); color: var(--ink); font-weight: 600; font-size: var(--t-sm); line-height: 1.2; text-decoration: none; }
.sp-btn:hover { border-color: var(--ink-3); }
.sp-btn.sp-primary { background: var(--accent); border-color: var(--accent); color: var(--accent-ink); }
.sp-btn.sp-primary:hover { filter: brightness(1.08); }
.sp-label, .sp-eyebrow, .sp-kind { font-family: var(--font-mono); font-size: var(--t-xs); letter-spacing: 0.08em; text-transform: uppercase; color: var(--ink-3); font-weight: 600; }
.sp-sub { color: var(--ink-2); font-size: var(--t-sm); }

/* ---------- Page head ---------- */
.sp-crumbs ol { list-style: none; margin: 0; padding: 0; display: flex; flex-wrap: wrap; gap: var(--s-1) var(--s-2); font-size: var(--t-sm); color: var(--ink-2); }
.sp-crumbs li + li::before { content: "›"; margin-right: var(--s-2); color: var(--ink-3); }
.sp-hero { display: grid; gap: var(--s-3); }
.sp-hero h1 { font-size: clamp(1.9rem, 5vw, var(--t-3xl)); }
.sp-lede { font-size: var(--t-lg); color: var(--ink-2); line-height: 1.5; }
.sp-meta { display: flex; flex-wrap: wrap; gap: var(--s-1) var(--s-3); font-size: var(--t-sm); color: var(--ink-3); align-items: baseline; }
.sp-meta > * + *::before { content: "·"; display: inline-block; margin-right: var(--s-3); color: var(--ink-3); text-decoration: none; }
.sp-meta a { font-weight: 600; }
.sp-cta { display: flex; flex-wrap: wrap; gap: var(--s-2) var(--s-4); align-items: center; margin-top: var(--s-2); }
.sp-cta-note { color: var(--ink-2); font-size: var(--t-sm); flex: 1 1 18rem; }
.sp-cta-end { justify-content: center; padding: var(--s-4) 0 0; border-top: 1px solid var(--rule); }

.sp-toc { background: var(--panel); border: 1px solid var(--rule); border-radius: var(--r-md); padding: var(--s-4) var(--s-5); display: grid; gap: var(--s-2); }
.sp-toc ol { margin: 0; padding-left: 1.6em; display: grid; gap: 2px; }
.sp-toc-end { list-style: none; margin: 0; padding: var(--s-2) 0 0; border-top: 1px solid var(--rule); display: grid; gap: 2px; }
.sp-toc li::marker { font-family: var(--font-mono); color: var(--ink-3); font-size: var(--t-sm); }
.sp-toc a { text-decoration: none; display: inline-flex; flex-wrap: wrap; gap: 0 var(--s-2); align-items: baseline; }
.sp-toc a:hover span:last-child { text-decoration: underline; }
.sp-toc-kind { font-family: var(--font-mono); font-size: var(--t-xs); color: var(--ink-3); text-transform: uppercase; letter-spacing: 0.06em; }
/* Titles line up: the kind sits in a column of its own on wide screens, and after the title on a phone. */
@media (min-width: 521px) {
  .sp-lesson .sp-toc ol a { display: grid; grid-template-columns: 8.5em minmax(0, 1fr); }
  .sp-lesson .sp-toc ol a > span:only-child { grid-column: 2; }
}
@media (max-width: 520px) {
  .sp-toc-kind { order: 2; }
}

/* ---------- Sections and blocks ---------- */
.sp-seg { display: grid; gap: var(--s-4); scroll-margin-top: var(--s-4); }
.sp-seg > h2 { font-size: clamp(1.5rem, 4vw, var(--t-2xl)); margin-top: calc(-1 * var(--s-2)); }
.sp-seg + .sp-seg { border-top: 1px solid var(--rule); padding-top: var(--s-6); }
.sp-seg h3 { font-size: var(--t-lg); }
.sp-main .prose { max-width: none; }
.sp-main .math-display { overflow-x: auto; overflow-y: hidden; padding: var(--s-1) 0; }

.sp-note, .sp-widget, .sp-q, .sp-worked, .sp-predict, .sp-explain, .sp-recall, .sp-keyideas-box, .sp-reveal {
  display: grid; gap: var(--s-3); border-radius: var(--r-md); padding: var(--s-4) var(--s-5); min-width: 0;
}
.sp-note { background: var(--panel-2); }
.sp-note-misconception, .sp-note-guess { background: var(--one-soft); }
.sp-note-misconception > .sp-label, .sp-note-guess > .sp-label { color: var(--one-label); }
.sp-note-guess { border-left: 3px dashed var(--one); }
.sp-note-key { background: var(--panel); border: 2px solid var(--accent); }
.sp-note-key > .sp-label { color: var(--accent); }
.sp-note-warning { background: var(--warn-soft); }
.sp-note-warning > .sp-label { color: var(--warn); }

.sp-widget { border: 1px dashed var(--ink-3); background: var(--paper); gap: var(--s-2); }
.sp-widget > .sp-label { color: var(--accent); }
/* A program (code widget, code question): as written, scrolling sideways rather than wrapping. */
.sp-code { margin: 0; padding: var(--s-2) var(--s-3); max-width: 100%; overflow-x: auto; background: var(--panel-2); border: 1px solid var(--rule); border-radius: var(--r-sm); font-family: var(--font-mono); font-size: var(--t-sm); line-height: 1.55; }
.sp-code code { background: none; padding: 0; font-size: inherit; white-space: pre; }
.sp-custom-head { font-weight: 650; }
/* A lesson's own drawing (a custom block with no controls), written out as the app draws it. */
.sp-custom-figure figure { margin: 0; display: grid; gap: var(--s-2); min-width: 0; }
.sp-custom-figure figcaption { color: var(--ink-2); }
.sp-try a { font-weight: 600; }
.sp-try a::after { content: " →"; }
.sp-caption { color: var(--ink-2); font-size: var(--t-sm); }

.sp-q, .sp-predict, .sp-explain, .sp-recall { background: var(--panel); border: 1px solid var(--rule); border-left: 3px solid var(--accent); }
.sp-q > .sp-label, .sp-predict > .sp-label, .sp-explain > .sp-label, .sp-recall > .sp-label { color: var(--accent); }
.sp-prompt { font-weight: 500; }
.sp-opts { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-2); }
.sp-opts li { display: grid; grid-template-columns: 1.9em minmax(0, 1fr); gap: var(--s-2); align-items: baseline; padding: var(--s-2) var(--s-3); border: 1px solid var(--rule); border-radius: var(--r-sm); background: var(--paper); }
.sp-letter { font-family: var(--font-mono); font-weight: 600; color: var(--ink-3); }
.sp-items { margin: 0; padding-left: 1.4em; display: grid; gap: var(--s-1); }
.sp-match { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 14rem), 1fr)); gap: var(--s-3) var(--s-5); }
.sp-match > div { display: grid; gap: var(--s-2); align-content: start; }
.sp-pairs { border-collapse: collapse; width: 100%; font-size: var(--t-sm); }
.sp-pairs td { border-top: 1px solid var(--rule); padding: var(--s-2) var(--s-2) var(--s-2) 0; vertical-align: top; }
.sp-pairs td:first-child { width: 50%; }
.sp-pairs td:last-child::before { content: "→ "; color: var(--ink-3); }
.sp-blank { color: var(--ink-2); }

.sp-answer, .sp-hint { border-top: 1px solid var(--rule); padding-top: var(--s-2); }
.sp-answer summary, .sp-hint summary, .sp-reveal summary { cursor: pointer; font-weight: 600; color: var(--ink-2); min-height: 32px; display: flex; align-items: center; gap: var(--s-2); }
.sp-answer summary::-webkit-details-marker, .sp-hint summary::-webkit-details-marker, .sp-reveal summary::-webkit-details-marker { display: none; }
.sp-answer summary::before, .sp-hint summary::before, .sp-reveal summary::before { content: "+"; font-family: var(--font-mono); color: var(--accent); width: 1em; }
.sp-answer[open] summary::before, .sp-hint[open] summary::before, .sp-reveal[open] summary::before { content: "−"; }
.sp-answer summary { color: var(--accent); }
.sp-answer-body { display: grid; gap: var(--s-3); padding-top: var(--s-2); }
.sp-hint ol, .sp-why-not { margin: var(--s-2) 0 0; padding-left: 1.3em; display: grid; gap: var(--s-2); }
.sp-reveal { border: 1px solid var(--rule); background: var(--panel); padding-block: var(--s-2); }
.sp-reveal[open] { padding-bottom: var(--s-4); }

.sp-worked { background: var(--panel); border: 1px solid var(--rule); }
.sp-steps { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-4); counter-reset: step; }
.sp-step { counter-increment: step; display: grid; gap: var(--s-2); padding-left: 2.4em; position: relative; min-width: 0; }
.sp-step::before { content: counter(step); position: absolute; left: 0; top: 0.1em; width: 1.7em; height: 1.7em; border-radius: 50%; display: grid; place-items: center; font-family: var(--font-mono); font-size: var(--t-xs); font-weight: 600; border: 1.5px solid var(--accent); color: var(--accent); background: var(--paper); }
.sp-your-turn::before { background: var(--one); border-color: var(--one); color: var(--panel); }
.sp-your-turn > .sp-q { border-left-color: var(--one); padding: var(--s-3) var(--s-4); }
.sp-step-label { font-weight: 650; }

.sp-recall-list { margin: 0; padding-left: 1.4em; display: grid; gap: var(--s-3); }
.sp-recall-list > li { display: grid; gap: var(--s-2); }
.sp-toolkit { font-size: var(--t-sm); color: var(--ink-2); }
.sp-toolkit a { font-weight: 600; }
.sp-keyideas-box { background: var(--panel); border: 1px solid var(--rule); }
.sp-keyideas { margin: 0; padding-left: 1.4em; display: grid; gap: var(--s-3); }
.sp-keyideas li::marker { font-family: var(--font-mono); color: var(--accent); font-weight: 600; }

/* ---------- Lists of links: go further, refreshers, lessons ---------- */
.sp-further, .sp-links { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-3); }
.sp-further li { display: grid; gap: 2px; padding: var(--s-3) var(--s-4); border: 1px solid var(--rule); border-radius: var(--r-md); background: var(--panel); }
.sp-further a { font-weight: 650; font-size: var(--t-md); }
.sp-by { font-family: var(--font-mono); font-size: var(--t-xs); color: var(--ink-3); letter-spacing: 0.02em; }
.sp-further p { color: var(--ink-2); font-size: var(--t-sm); }
.sp-links li { display: grid; gap: 2px; }
.sp-links a { font-weight: 650; }
.sp-links span { color: var(--ink-2); font-size: var(--t-sm); }

.sp-pager { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(100%, 16rem), 1fr)); gap: var(--s-3); }
.sp-pager a { display: grid; gap: 2px; padding: var(--s-3) var(--s-4); border: 1px solid var(--rule); border-radius: var(--r-md); background: var(--panel); text-decoration: none; font-weight: 650; }
.sp-pager a:hover { border-color: var(--accent); }
.sp-next { text-align: right; }
/* After the last lesson: the next part, still to come. Dashed and muted, not a link. */
.sp-pager .sp-soon { display: grid; gap: 2px; padding: var(--s-3) var(--s-4); border: 1px dashed var(--ink-3); border-radius: var(--r-md); color: var(--ink-2); font-weight: 650; }

.sp-cards { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-3); }
.sp-card { display: grid; gap: var(--s-2); padding: var(--s-4) var(--s-5); border: 1px solid var(--rule); border-radius: var(--r-md); background: var(--panel); }
.sp-card h2 { font-size: var(--t-xl); }
.sp-card h2 a { text-decoration: none; }
.sp-card h2 a:hover { text-decoration: underline; }

/* ---------- Home: pre-rendered inside the app page with the app's own classes (replaced when the app boots) ---------- */
.sp-home .sp-foot { margin-inline: calc(-1 * max(16px, env(safe-area-inset-left, 0px))); margin-bottom: calc(-1 * var(--s-8)); }
/* A lesson row is not one link here (its title links to the lesson's page, "Start" into the app),
   so the title is an h3 drawn exactly like the app's span. */
.sp-home .map-link:hover { background: none; }
.sp-home h3.map-title { font-size: var(--t-lg); line-height: inherit; letter-spacing: -0.01em; text-wrap: wrap; }
.sp-home .map-title a { color: var(--ink); text-decoration: none; }
.sp-home .map-title a:hover { color: var(--accent); text-decoration: underline; }
.sp-home .map-meta a { font-weight: 600; }

@media (max-width: 520px) {
  /* Logo and button on the first row, the nav under them. */
  .sp-top-in { gap: var(--s-2) var(--s-3); }
  .sp-nav { order: 3; flex-basis: 100%; margin-left: -0.7em; }
  .sp-open { min-height: 40px; }
  .sp-q, .sp-predict, .sp-explain, .sp-recall, .sp-worked, .sp-note, .sp-widget, .sp-keyideas-box { padding: var(--s-3) var(--s-4); }
  .sp-step { padding-left: 2.1em; }
  .sp-toc { padding: var(--s-3) var(--s-4); }
}

@media print {
  .sp-top, .sp-foot, .sp-cta, .sp-toc, .sp-pager, .sp-skip { display: none; }
  .sp-answer, .sp-hint { break-inside: avoid; }
}

/* The amber label on --one-soft: a deeper amber in light mode keeps it above 4.5:1. */
:root { --one-label: #9a5200; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) { --one-label: var(--one); } }
:root[data-theme="dark"] { --one-label: var(--one); }